Marshalling & Unmarshalling
"Marshalling" is the process of converting a higher-level (object) structure into some kind of lower-level representation (and vice versa), often a binary wire format. Other popular names for it are "Serialization" or "Pickling".
In akka-http "Marshalling" means the conversion of an object of type T into an HttpEntity, which forms the entity body of an HTTP request or response (depending on whether used on the client or server side).
Marshalling
On the server-side marshalling is used to convert an application-domain object to a response (entity). Requests can
contain an Accept header that lists acceptable content types for the client. A marshaller contains the logic to
negotiate the result content types based on the Accept and the AcceptCharset headers.
Marshallers can be specified when completing a request with RequestContext.complete or by using one of the
RouteDirectives.complete directives.
These marshallers are provided by akka-http:
- Use Json Support via Jackson to create an marshaller that can convert a POJO to an
application/jsonresponse using jackson.- Use
Marshaller.stringToEntity,Marshaller.byteArrayToEntity,Marshaller.byteStringToEntity, combined withMarshaller.entityToResponseto create custom marshallers.
Unmarshalling
On the server-side unmarshalling is used to convert a request (entity) to an application-domain object. This is done
in the MarshallingDirectives.request or MarshallingDirectives.entity directive. There are several unmarshallers
provided by akka-http:
- Use Json Support via Jackson to create an unmarshaller that can convert an
application/jsonrequest to a POJO using jackson.- Use the predefined
Unmarshaller.entityToString,Unmarshaller.entityToByteString,Unmarshaller.entityToByteArray,Unmarshaller.entityToCharArrayto convert to those basic types.- Use
Unmarshaller.syncorUnmarshaller.asyncto create a custom unmarshaller.
Contents
